Various display devices are known for realizing stereoscopic vision by observing two images with parallax by an image observer. As a naked-eye type display device, practical realization of a display device obtained by combining an optical separating unit formed of a parallax barrier or a lens sheet provided with a lens array and a display unit displaying a two-dimensional image is promoted.
A conceptual diagram of operation of the naked-eye type display device is illustrated in FIG. 30.
In FIG. 30, a group of rays emitted from pixels with reference signs 1R, 3R, 5R, 7R, and 9R reaches a viewpoint 1 and a group of rays emitted from pixels with reference signs 2L, 4L, 6L, 8L, and 10L reaches a viewpoint 2. Therefore, at a position apart from the display unit by a predetermined distance, the image at the viewpoint 1 and the image at the viewpoint 2 are independently observed.
When a right eye and a left eye of the image observer are positioned at the viewpoint 1 and the viewpoint 2 respectively, if a right-eye image is displayed by the pixels with reference signs 1R, 3R, 5R, 7R, and 9R and a left-eye image is displayed by the pixels with reference signs 2L, 4L, 6L, 8L, and 10L, the image observer recognizes the image as a stereoscopic image.
If the image observer observes the image at a position deviated from the viewpoint 1 and viewpoint 2, images for different viewpoints are mixedly observed. Herein, the fact that the images for different viewpoints are mixedly observed is referred to as crosstalk. The crosstalk damages a stereoscopic effect. Also, by observing the image at a position deviated far away, a state such as “reverse viewing” in which the left-eye image and the right-eye image are displaced with each other occurs. The image observer perceives the image in which the front and the back are inverted, and feels unnatural or uncomfortable.
In order to solve such a problem, for example, a display device in which a position of an image observer is detected and contents of an image to be displayed on a display unit are changed is proposed (refer to Patent Document 1).